Reproductive and Fiber Quality Responses of Upland Cotton to Moisture Deficiency

Abstract

Quantitative information between water deficit and cotton (Gossypium hirsutum L.) reproductive potential and fiber quality is needed to improve cotton model predictability. An experiment was conducted by seeding Upland cotton cultivar, Texas Marker (TM)‐1, in sunlit growth chambers. Four water stress treatments, 100, 80, 60, and 40% of daily evapotranspiration of the control, were imposed during flowering for plants grown at optimum temperature and nutrient supply. Soil moisture content and midday leaf water potential (LWP) were measured twice weekly during treatment period. Photosynthetic measurements taken during the stress treatments were correlated with midday LWP. New flowers and bolls were tagged daily to estimate boll maturation period (BMP). Plant‐ and boll‐component dry weights were recorded at end of the experiment. Lint sample collected, grouped based on average LWP during BMP, were analyzed for fiber quality parameters. Declining photosynthetic rates as plants experience water deficits were mostly to stomatal limitation, but non‐stomatal factors played a role as stress progressed. Seedcotton and seed weight, boll numbers, and total biomass declined significantly at severe water deficit treatments reflecting declining trends of photosynthesis. Fiber length, strength, and uniformity declined linearly with decrease in LWP, whereas fiber micronaire increased with decrease in LWP. Fiber strength was most responsive to changes in LWP followed by micronaire, length, and uniformity. Immature fiber content increased and fiber maturity ratio declined with diminishing LWP. The functional relationships between LWP and fiber properties will be useful to develop fiber sub‐models under optimal temperature and nutrient, but varying moisture conditions.